A new study has found that women's breasts age more quickly than some other tissue in the female body.

Researchers from the University of California, Los Angeles (UCLA) -- led by Steve Horvath -- used epigenetics to determine the age of certain human tissue, thus identifying the overall age of the person. Epigenetics is when genes have methyl chemical groups added or removed, which increases or decreases gene expression. This changes the chemical markings on our DNA as we age.

The team began by looking at methylation patterns in 7844 healthy tissue samples from 51 different types of tissue, where ages ranged from fetuses to 101-year-old humans.

The UCLA team then sorted through methylation patterns that varied between tissues and those that are common to all tissues. They narrowed it down to a subset of 353 specific regions of the genome that became more or less methylated with age in nearly all types of tissue.

From there, they created an algorithm that determined the age of the tissue. The algorithm was tested against tissues with known ages, and according to Horvath, this method is twice as accurate as measuring the length of telomeres (these are the tips of chromosomes that decrease in length as we age).

Also, Horvath said that this method has 96 percent accuracy when it comes to determining age compared to the measuring of telomeres, which only has an accuracy of about 53 percent.

The study found that some tissue aged much faster than the human's overall age, such as the female breast. The algorithm found that the female breast tissue of women around 46 years of age ages an average of two to three years older than the overall age of the woman. Horvath thinks this is because the tissue is exposed to hormones.

The team also found that cancerous tissue ages prematurely at about 36 years older than a person's actual age (this applies to 20 cancers across 20 different tissues).